From c38c80fd43aef943700826c35fd4597d5fffdb0c Mon Sep 17 00:00:00 2001
From: Norman Feske <norman.feske@genode-labs.com>
Date: Thu, 18 Apr 2019 13:17:53 +0200
Subject: [PATCH] menu_view: midway re-targeting of geometry motion

This patch fixes the corner case where an animated geometry changes its
destination mid-way while an animation is already in progress. The
'_trigger_animated_geometry' method used to back out early in this case,
which was intended as an optimization.

Fixes #3296
---
 repos/gems/include/gems/animated_geometry.h | 11 +++++++++++
 repos/gems/src/app/menu_view/widget.h       |  3 ---
 2 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/repos/gems/include/gems/animated_geometry.h b/repos/gems/include/gems/animated_geometry.h
index 854d38a46f..1a3a20a1b0 100644
--- a/repos/gems/include/gems/animated_geometry.h
+++ b/repos/gems/include/gems/animated_geometry.h
@@ -64,6 +64,8 @@ class Genode::Animated_rect : private Animator::Item, Noncopyable
 
 		Animated_point _p1 { }, _p2 { };
 
+		Steps _remaining { 0 };
+
 	public:
 
 		Animated_rect(Animator &animator) : Animator::Item(animator) { }
@@ -77,6 +79,9 @@ class Genode::Animated_rect : private Animator::Item, Noncopyable
 
 			_rect = Rect(Point(_p1.x(), _p1.y()), Point(_p2.x(), _p2.y()));
 
+			if (_remaining.value > 1)
+				_remaining.value--;
+
 			/* schedule / de-schedule animation */
 			Animator::Item::animated(_p1.animated() || _p2.animated());
 		}
@@ -90,6 +95,12 @@ class Genode::Animated_rect : private Animator::Item, Noncopyable
 		 */
 		void move_to(Rect rect, Steps steps)
 		{
+			/* retarget animation while already in progress */
+			if (animated())
+				steps.value = max(_remaining.value, 1U);
+
+			_remaining = steps;
+
 			_p1.move_to(rect.p1(), steps);
 			_p2.move_to(rect.p2(), steps);
 			animate();
diff --git a/repos/gems/src/app/menu_view/widget.h b/repos/gems/src/app/menu_view/widget.h
index b08b5387aa..5f78d66be1 100644
--- a/repos/gems/src/app/menu_view/widget.h
+++ b/repos/gems/src/app/menu_view/widget.h
@@ -163,9 +163,6 @@ class Menu_view::Widget : List_model<Widget>::Element
 
 		void _trigger_geometry_animation()
 		{
-			if (_animated_geometry.animated())
-				return;
-
 			bool const changed = (_geometry.p1() != _animated_geometry.p1()
 			                   || _geometry.p2() != _animated_geometry.p2());
 			if (changed)